【作者】 齐学洁；

【导师】 王长生；

【作者基本信息】 辽宁师范大学 ， 物理化学， 2004， 硕士

【摘要】 本文采用密度泛函理论B3LYP方法,对不同多肽构象体系进行了理论研究。探讨影响氢键性质的主要因素,并对氢键键能进行了初步估算。优化了各个构象,计算各个结构的单点能。本论文主要研究了以下几个方面:以β-stand、27-ribbon、以及310-helix和α-helix结构为研究对象,分别对形成N-H…O=C结构的各个原子电荷进行了研究,讨论了能影响氢键性质的各种因素,并分析了导致氢键强度性质协同性的主要原因。分别以含有甲基侧链和无甲基侧链的二肽以及三肽结构为研究对象,在保持其他位置原子不变的情况下,用C原子取代形成氢键的N原子,以全铺展结构作为基准,初步估算了“氢键键能”;用与形成氢键的O原子同主族的S原子取代O原子,仍然以全铺展结构作为基准,初步估算了“氢键键能”。更多还原

【Abstract】 A Theoretical Study on the Hydrogen Bond Properties in Polyglycine PeptidesA theoretical study on the hydrogen bond properties in peptides was carried out by using a simple repeating unit method with B3LYP/6-31G* method. The factors influenced the hydrogen bond strength was discussed. The hydrogen bond energy in polypeptides was estimated. The details are:Four conformations have been studied including strand, 27?ribbon, 310?helix and helix up to 26 repeat units for a series of polyglycine model. The charges have been analyzed and the hydrogen bond strengths have been obtained. The hydrogen bond strengths are clearly indicated by the hydrogen bond acidities and the partial charges of the hydrogen atoms, which have been involved in the formation of the hydrogen bond. There does exist the cooperativity among the hydrogen bonds in the 310-helix and helix structures of peptides. The more the numbers of the hydrogen bonds in the helix structure, the stronger each hydrogen bond is.The NH group was replaced by CH2 in glycine di- /tri-peptide and alanine di-/tri-peptide to estimate the hydrogen bond energy. The HB energy was estimated varied from 2.9 to5.0kcal/mol in different systems. This is insistent with the empirical values.更多还原